Process for the production of paper-pulp or cellulose from bamboo and the like.



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BIKE, 0F PENICUIK, SCQTLANE.

THE LIKE.

1i 143, shill,

no memos.

T all whom it-may comm:

Be it" known that I, JAMEs LOCKHART J'ARnINn, a subject of the King of Great Britain and Ireland, and a resident of Penicuih, Midlothien, Scotland, have invented 22 contain new and. useful Process for the Production of Paper-Pulp or Gellulose from Bamboo and the like,- of which the follow ing is the specification.

A commercially hlea'chahle pulp connoc'be produc d from bamboo or simile'n vegetable growths the incrusting ingredienis of which are mixtures of lignin and pectose, or substances chemically si'mileir, by any of the hisulfiie processes as employed for extra?- iion of pulp from wood enil the like lignifi ed substances. 1 have discovered thee this is due to the excessive acioiiy oi?- the liquor as used in ihe process of digestion, caused by she liher'eiion and retention in the digester oi the sulfufous acid g es Alt preseni iii-the Wood'pulp process where the digester is internally heoiefi, the sulfurous acid gas liberated in the heating and cooking is, as for as practicable, keptin con met with ihe pulp, an& only quantities are allowed to escape from the digest-en sufficient to'admii of the entrance of enough siea'ni "to secure and maintain the'proper cooking hempereture, this being control-led hy direct thermometer ieaolings.

Ii? bamboo enfi ihe like he ireeieol in a similar manner, a secondary reaction occurs in the loser stages oi ihe' cooking which upsets the chemical equilibrium snol e brown aldehyolic proolucz'c is deposited on ih'e fibers, rendering ihem commercially unbleecheble, or ii the hydrolysis is lessened to prevent the deposition of this organic reducing og'eni the resolution is incomplete, and oli-hougiie light yeliow colored pulp can be secured ii; does not hleoich es fibers are shill combined Wiih on inoeseii incsusizingingredieni's.

My inven'iion consists a process Where by these diliicnlties one overcome, my method insuring that the ligno enol pecl'rio consiii'w eni's, Jilfllig with the coloring; 'inoioiers, and the like, are so thoroughly removed i'hsi ilie suhsequeni oleechingg "for the prooluocion oi a Whi'ie fulp does'noi need more of the usual hleeohing agents then one requireol for pulps elrescl" use" in. creole.

:iormin ihe sohjeci moose? inveniion,

Specificeiion of Letters Batent;

.fippliceiion fi-led-August-S, 1914. Serial 1%; 835,473.

Patented June 355, iiil5o a soluble sulfiie must be selected, such as magnesium, or sodium; or their equivalents, and to ii is added in any conv'en'iehi' manner sulfurou's acid gas as in cerceiu known processes for the resolution of wood, hut accordinge0 the-invention these chemicals are so used for the production of paper pulp from bamboo and the like that the deposition of on aldehyde is prevented anci only the proper degree of acidityis meini'eineii to sulfonaiie the lignin, leaving the hose free to resolve the pectic and coloring ingredients.

Magnesia does 110%- resdilfy dissolve in Weak sulfurous acid, and thuswhen its soluiion is efieciecihy any of the ordinary processes, the resultant liquor generally showsoi least the hislllfiie proportions oi 5%), So iiium sulfiie on the other heui is readily soluble, a'ncl a solution conheining approx mately these-fifths of the hisulfite equivalent provides a liquor with a surplus of evoilehle 0 so rendering ii suitehle for my prooe'ss: Such a solution may contain ahouu five atoms of sodium to three of sulfur.

ln'ordei that the fibrous tissues my my idly and uniformly ohsorh the Home, their colloidal adhesions must he hookers clown by mechanical crushing. The new meierial eiier receiving this preliminary hoeetinoni' is packed a oli'gesten, the picpei esl liquor is adcleol, and iho heating enfl cooking is secures by the application oi iiireoi-v sieum;

it is ailvisahle not to fill the, sier too full, as space is necessary for the fires seperation of the gases evolved from liquor, and as these are liberated they niust' it once he removed, and for ihis pussies-o econ" iueusiy free oiihe'usi ii'i ied in one i of the digests? is kept open ihnoi; eniire cooking. The escaping sieeu? may he pesseii to a cooling coil ing eppereitus for linown mansion.

So ihonoughly must neinoveil ihec no oppo D in the (ligesitr'er; the oon hire is hos' oi all she o folio Beam LQX'GEQEEEIS, neoi he Throughout the digestion by the removal of the gasified SO the degree of active acidity automatically regulates itself to suit the condition of the pulp and the holding capacity of the base; thus there are no complications, and resolution proceeds along regular lines.

To secure the complete removal of the in crusting ingredients, or complete decortication, suiiicient free or available sulfurous acid to sulfonate the lignin must be provided, and as variations in the proportions of this substance occur, it is advisable to have excess sulfurous acid in the liquor at the start of the digestion, the surplus being liberated and readily removed in the manner already described. Or the excess may be otherwise removed.

Any increase in, the proportion of the pectose constituents requlres a correspond ing increase in the percentage of the base, but underall conditions excess of this must be provided, as it insures complete resolution and the consequent slow reduction of the liquor strength in the last stages of the cookin Having enumerated the princi les of my invention, I now give working etails of a method as applied to the common bamboo of the West Indies. This bamboo must be very thoroughly and uniformly crushed, cut

into convenient lengths, and packed into a vertical digester with acid proof lining. Between 10 and 12 lbs. of the crushed material can easily be packed into each cubic foot capacity of the digester, and about one gallon of liquor is required for two lbs. of bamboo, or on the weight basis this means roughly five to one. A suitable liquor made in a known manner from a magnesium base gives the following S0 analysis Total SO 3. 25% Available or free; 1.80%

Combined 1. 45%

tion apparatus forming part of the liquormaking plant. The steam is applied to the digester, and the full gage pressure of lbs. or 5 atmospheres is reached in three to four hours. The air and surplus sulfurous acid'come 03 very rapidly durin the heating up of the contents, and the fu 1 capacity of the outlet is then required; but thereafter, to prevent steam waste, it can be curtailed by partially shutting the outlet control cook. The rate of gas liberation in the further stages of the cooking is relatively slow, and thus a smaller outletis sufiicient. Under these circumstances the condensation of steam in the cooling coil during the cooking amounts to 15%, or 20% of the volume of the liquor added, and the sulfurous acid recovered is 20% to 25% of the original.

The removal of the surplus or gasified S0 is necessary for the chemical reasons already stated, for if this is not thoroughly effected the acid unduly preponderates, preventing the alkaline base from having freedom to remove the pectose constituents, or completely upsetting the chemical equilibrium and depositing the aldehyde.

Care must therefore be taken to insure that all the gasified SO escapes from the liquor, and toa certain extent the process can be hurried by arranging for a larger steam escape in the later stages of the cooking, as this more rapidly carries ed the traces of free 80,, allowing the base to more quickly effect the removal of the coloring and gummy substances.

After reaching full pressure, ten to twelve hours are required to complete the cooking process, this being carried on until the percentage of total sulfurous acid in the liquor, as ascertained by direct test with standard iodin solution, is very much reduced. A suitable and satisfactory final strength, where dry steam has been used, is about .1%. When this stage is reached the steam is shut ofi, and that contained in the digester is either blown out direct to atmos phere, or it can be condensed through a cooling coil, though the latter process is not necessary from the point of view of sulfur economy, seeing the bulk of this element which is not required in the chemical action has already escaped and been recovered. After the pressure has been sufliciently reduced, the contents of the digester are blown out, and the resultant pulp is of a grayish-white color. The yield is fully 50% of the original weight of bamboo furnished.

The pulp can be bleached by ordinary methods to a full white with about 12% of bleaching powder calculated on the dry weight of pulp.

What I claim is 1. A process of producing easily bleachable paper pulp from bamboo and the like, which comprises cooking said material, in a crushed condition, under pressure, with a solution of a water-soluble sulfite containing, at the commencement of the cook, an excess of available SO over the amount 12o necessary to form normal sulfite, and maintaining said liquor, durin the latter part of the cook, substantially ree from uncombined S0 by relieving the gas pressure at such a rate that substantially all the liberated S0 is drawn ofi, and thereby prevented from accumulating in the liquor.

2. A process of producing easily bleachable paper pulp from bamboo and the like, which comprises cooking said material, in a crushed condition, under. pressure, with a solution of magneslum blsulfite containing, at the commencement of the cook, an excess of available SO over the amount necessary to form normal sulfite, and maintaining said liquor, during the latter part of the cook, substantially free from uncombined S0 by relieving the gas pressure at such a rate that substantially all the liberated 

